The present invention relates generally to evaporative cooling devices and, more particularly, to a lightweight evaporative cooler which is highly efficient, resistant to spillage, inexpensive, and easy to construct. The evaporative cooler of the present invention finds particular utility as a roof-mounted unit for providing sensible cooling of an interior compartment of a moving vehicle or other movable structure, such as automobiles, vans, buses, recreational vehicles, motor homes, travel trailers, pop-up campers, cargo/parcel distribution vehicles, horse trailers, livestock trailers, watercraft, tents and other portable dwellings, and the like, and will be described in particular reference thereto. However, it will be recognized that the present invention is also applicable to cooling interior spaces of buildings, dwellings, and the like, as well as other structures and interior confines, or otherwise for providing a cooled and/or humidified environment to animals, plants, humans, fish, perishable items or temperature-sensitive items, or any other organic or man-made substance that would benefit from cooling and/or humidification.
In conventional evaporative coolers, water is circulated in a downward direction on a vertically mounted pad. The free flowing water encounters air that is pulled horizontally through the pad. The conventional pad design employing free flowing water is disadvantageous in that it floods or covers the surface of the pad, thus reducing the surface area of the evaporative material available to make contact with the air. Such conventional coolers are fashioned after industrial cooling tower design and circulate large volumes of water past large volumes of air. The result is that the both the water and the air are cooled from the latent heat of evaporation. The free flowing water design of a conventional pad also reduce efficiency by reducing the surface area available to make contact with the air by flooding the irregular surface of the pad.
In a first aspect, an evaporative cooler includes a compact housing having a top panel, a base panel aligned with the top panel, and one or more side panels peripherally disposed between the upper and base panels. An air inlet formed in the upper panel and a plurality of openings providing air outlets are formed in at least one of the one or more side panels. The base panel is adapted to collect excess evaporation water and an air pervious evaporative pad formed of a fibrous material is enclosed within the housing. The evaporative pad comprises a base portion located within the base panel and peripherally raised portion extending between the base portion and the top panel and enclosed by the one or more side panels. The peripherally raised portion defines a cavity within the evaporative pad which is generally aligned with and opens toward the air inlet. A fan secured to the top panel directs air ambient the fan into the housing and through the evaporative pad where it is cooled. The cooled air is discharged through the air outlets. A conduit and flow control system is provided to supply evaporation water to the evaporative pad at a rate substantially equal to the rate at which the water evaporates.
In a second aspect, a method for cooling a space, comprises providing an evaporative pad contained within a housing and introducing water into the housing for absorption by the pad. The pad comprises a base portion and peripherally raised walls and is formed from a water absorbing and air pervious material. The housing comprises a water-tight base and an air outlet. A volume of air from outside the space is directed into the recess in the pad and the air is cooled by passing it through the pad and delivered into the space to be cooled. Unabsorbed water is collected in the base and it is determined whether excess unabsorbed water is present in the base. If unabsorbed water in excess of a predetermined quantity is sensed, the supply of water is shut off until the excess water has evaporated.
In a third aspect, a cooler pad for an evaporative cooler includes a base layer and a plurality of peripherally raised walls formed of an air pervious fibrous material. Each peripherally raised wall has a first side forming a peripheral side of the pad and an opposite second side facing a recess formed in the pad for receiving water.
One advantage of the present invention is the provision of an improved evaporative cooler which can replace or which can be used in conjunction with a compressor-type air conditioning unit.
Another advantage of the present invention is the provision of a cooler which is primarily designed to cool air, not water.
Another advantage of the present invention is an improved pad design with a center intake and three hundred and sixty-degree discharge design. This reduces the back pressure against which the fan must work, allowing the use of axial fans instead of blower-type or squirrel cage fans.
Another advantage of the present invention resides in its pad design which allows placement of the fan upstream of the evaporative pad, thus reducing the noise in the living area.
Still another advantage of the present invention is that is compact enough to allow the entire cooling chamber to be located within the living area, and thus, does not absorb heat from outside air or radiant heat from the sun.
Yet another advantage is the provision of an evaporative cooler having increased efficiency. The industry standard temperature differential is about 11xc2x0 C. (20xc2x0 F.). The cooler according to the present invention runs at about a 20xc2x0 C. (35xc2x0 F.) differential.
Yet another advantage of the present invention resides in that water does not accumulate, or is kept to a minimal amount, in the discharge pan. This obviates the need for drainage or the recycling of excess water and prevents water from sloshing or spilling out of the pan, even when the unit is tilted or used in a moving vehicle.
Another advantage is the compact design, which provide a light weight unit which can be mounted on a tent style pop-up camper or other vehicle type that could not support the weight of a conventional cooler, much less a compressor-type air conditioner.
Still another advantage of the subject invention is the reduced overall height, which allows the use of a shorter evaporator pad. This shorter pad allows the water to draw itself up into the pad at a high enough rate to eliminate the need for an internal pump to circulate water across the pad.